1. Field of the Invention
This invention relates generally to the shielding of electrical components from Electro-Magnetic Interference (EMI), and, more particularly, to the design and placement of shielding elements within a computer system.
2. Description of Related Art
Computer systems are general-purpose devices that may be modified to perform particular tasks or functions. Generally, computer systems include a motherboard, a power source and other components mounted within a cabinet. The motherboard typically includes a central processing unit (CPU) and a number of connectors or slots in which special purpose printed circuit boards, often referred to as peripheral component interface (PCI) bus cards or xe2x80x9ccardsxe2x80x9d, may be inserted. These special purpose cards may be used to add to or enhance the functionality of the computer system. For example, a conventional computer system may have its graphics capability enhanced by the addition of a graphics card. Similarly, the sound-producing capability of the computer system may be enhanced by the addition of a sound card.
The operation of electrical equipment, such as the CPU and printed circuit boards, disk drives, power supplies, and the like, can generate electric and magnetic field forces within the computer assembly. These forces can disrupt the operation of components and are generally referred to as electro-magnetic interference (EMI).
As technology has increased CPU clock speeds and shortened device rise times, the generation of high frequency electro-magnetic interference (EMI) has also increased. Conventional static shielding methods are useful for generally low frequency ( less than 200 Mhz) EMI, but do not provide the isolation needed at the higher frequencies.
Certain sensitive equipment and components need to be shielded from EMI that can adversely affect their operation. Removable peripheral devices such as hard disk drives and compact disk readers are typically located within a removable device compartment of the computer assembly and are electrically connected to the motherboard.
There is a need for improved methods and apparatus to reduce the disruptive effects of electro-magnetic interference (EMI), especially high frequency EMI, within computer assemblies.
One embodiment of the present invention is an electro-magnetic interference shielding apparatus for an electronic assembly comprising a shielding partition, the shielding partition separating a first compartment from a second compartment. The apparatus further comprises a top enclosure capable of engaging with the shielding partition to form a plurality of contact seams. The contact seams are capable of restricting electro-magnetic interference from passing through the shielding apparatus. The shielding partition can comprise apertures that are sized sufficiently small to restrict the passage of relatively high frequency electro-magnetic interference emissions. The top enclosure can be capable of tool-free installation and removal.
Another embodiment of the invention is a method for containing electro-magnetic interference emissions within a computer assembly. The method comprises separating a motherboard compartment from the rest of the computer assembly by inserting a shielding partition within an assembly housing. A shield assembly around the motherboard compartment is created by attaching a top enclosure to the housing and to the shielding partition, thereby creating a plurality of tortuous paths. The tortuous paths restrict the passage of electro-magnetic interference emissions through the shield assembly.